Alright listen up and pay attention dude because there's a lot of things in reading what you've said that are really ringing alarm bells with me. About a month ago i was diagnosed with whats called Scheuermann's Disease (shermans) and a lot of the symptoms you're describing are the same. Have you grown a lot recently? Like are you between 16-20yo? It's the breathing problem thing which concerns me the most. About 4 months ago i started to get progressively worse back pain, and i also thought it was because of my bars being too low, upgraded em, did nothing. Eventually it got to the point where i was having major problems breathing and pain all the time. I still have pain now. Haven't ridden in almost 4 months and i'm told that i may never ride again and that it will be at least 1-2 years before ill know for sure. What could be going on, and this is what happened to me, is if youre at the age where youre going to be growing, or your body is preparing for growth, your gorwth plates and bones in your spine become a lot softer and more malleable. This means theyre a lot easier to damage. Accompanied with the constant harsh impacts that all action sports give to your body, this could be crushing your vetrebrae, and squashing the your spinal discs. These discs have a series of nerves connected to them, which spread out all across your chest, especially the rib cage, and across your diaphragm. When these nerves are crushed they cause all the muscles theyre connected to to tighten up. This is what may be causing your shortness of breath. What concerns me even more is you're describing the exact area where my vertebrae are damaged. I have three permanently mishaped vertabrae in between my shoulder blades.
You need to go and see a chiropractor, and get an X'RAY done IMMEDIATELY. The longer you leave this and ride with this condition the worse it is for you. Avoid sitting down because this compresses your spine and makes it even worse.
Please go and get an x-ray immediately.